Re: [PATCH] PCI: PM: Fix PCIe MRRS restoring for Loongson

[Huacai Chen <chenhuacai@gmail.com>]

Hi, Bjorn,

On Wed, Jun 26, 2024 at 11:08 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Sun, Jun 23, 2024 at 11:39:40AM +0800, Huacai Chen wrote:
> > Don't limit MRRS during resume, so that saved value can be restored,
> > otherwise the MRRS will become the minimum value after resume.
> >
> > Cc: <stable@vger.kernel.org>
> > Fixes: 8b3517f88ff2983f ("PCI: loongson: Prevent LS7A MRRS increases")
> > Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> > ---
> >  drivers/pci/pci.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 35fb1f17a589..bfc806d9e9bd 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -31,6 +31,7 @@
> >  #include <asm/dma.h>
> >  #include <linux/aer.h>
> >  #include <linux/bitfield.h>
> > +#include <linux/suspend.h>
> >  #include "pci.h"
> >
> >  DEFINE_MUTEX(pci_slot_mutex);
> > @@ -5945,7 +5946,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq)
> >
> >       v = FIELD_PREP(PCI_EXP_DEVCTL_READRQ, ffs(rq) - 8);
> >
> > -     if (bridge->no_inc_mrrs) {
> > +     if (bridge->no_inc_mrrs && (pm_suspend_target_state == PM_SUSPEND_ON)) {
>
> I don't think we can check pm_suspend_target_state here.  That seems
> like a layering/encapsulation problem.  Are we failing to save this
> state at suspend?  Seems like something we should address more
> explicitly higher up in the suspend/resume path where we save/restore
> config space.
I'm sorry, after some deep analysis, we found this patch is
unnecessary, please ignore this.

Huacai

>
> >               int max_mrrs = pcie_get_readrq(dev);
> >
> >               if (rq > max_mrrs) {
> > --
> > 2.43.0
> >